PCB gold contacts

[pgross]

I’m wondering if there are any solutions to prevent wear and tear on gold
flashed PCB contacts. Some manufactures utilises some kind of oil on their contacts
and connectors, but while cleaning these contacts the oil will inevitably be washed away
and some new lubrication must be applied. The contact oil prevents oxidization and
maintain low resistance contact.

I know that Santolubes, http://www.santolubes.com manufactures contact oil ACCL
(Anti Corrosion Connector Lubricant), their products are widely used in the aerospace and
aviation industry. In my Company, we use their ACCL oil on small gold contacts carrying
very low audio signals and power. What about contact pads on PCB? As an example:
I want to clean the contact pads in a multimeter with Isopropanol, but I’m not sure if I
should apply contact oil afterwards. Are there any drawbacks using oil in this kind of
application?

Please let me know your opinion.

Best Regards

Peter

[Dave]

Gold doesn't oxidize.

[SeanB]

If the coating is thin and porous the copper underneath does, and if it wears through from wiping action the same applies. Use a lubricant on them, just use sparingly, just enough to have a thin sheen on the contacts only applied with a Q tip.

[Dave]

The pads on PCBs that are not intended for soldering, but for making contact with some other connector (e.g. edge connector on a PCI card) or switches (e.g. multimeter's range switch), get a much thicker gold coating. Not long ago someone posted a video showing the manufacturing process of a PCB. The pads that require a thick coating get a second immersion into the gold solution.

I'd put it like this: If you find lubricant inside the instrument you are working on, reapply the lubricant after you are done with the repairs. If there is nothing, I'd leave it that way.

[pgross]

Thanks for your comments.

Well, it is hard to see if the PCB range switch is lubricated. Between the gold pads I can see some very faint
black traces on the silkscreen - dont know if it is contamination from the wiper contacts or lubrication.

The Santolube ACCL oil I referred to is very thin and it seems to dry up almost invisible.

Best Regards

Peter
 

[fcb]

Typically there is ENIG (immersion gold - used to maintain solderability) and there is hard-gold (edge connectors), there is a cost difference.

I recently designed something with nickel coating, and we found huge differences between manufacturers as to scratch resistance (ranging from scratch it with a curved brass point, through to having to chisel at it to scratch it).

These guys are the nuts: http://www.p-m-services.co.uk/hard_gold.htm